NOVATO, CALIFORNIA—A construction project has prompted the excavation of a Mikwok Indian food-processing site near the waters of San Pablo Bay. In addition to arrowheads, parts of grinding bowls, and stone tools, archaeologists from the Sacramento State Archaeological Research Center and Caltrans have uncovered shell middens containing mussel and oyster shells. “This area probably would have been surrounded by brackish or saltwater marshes. There was also a freshwater creek nearby,” said Mark Basgall of California State University, Sacramento. He estimates that most of the artifacts at the site are about 1,000 years old, but the site was occupied as long as 3,000 years ago.